A.T. Robertson Commentary Luke 11:20

"But if I by the finger of God cast out demons, then is the kingdom of God come upon you." — Luke 11:20 (ASV)

By the finger of God (εν δακτυλω θεου). In distinction from the Jewish exorcists. Matthew 12:28 has "by the Spirit of God."

Then is come (αρα εφθασεν). Φθανω in late Greek comes to mean simply to come, not to come before. The aorist indicative tense here is timeless. Note αρα (accordingly) in the conclusion (αποδοσις).